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Why Is It So Important to Get Your Subfloor Right?

What is subflooring? And does it even matter? In this article, we take a look at what a subfloor is and how it impacts the overall performance and appearance of your floating floor.

Every flooring system has several layers including the structural joists, underlayment, surface flooring, and the subfloor. Some form of subfloor is found underneath every floor type, whether it’s hardwood, laminate, vinyl, carpet, or natural stone.

And just as your home’s foundation is critical to its structure, a subfloor plays a crucial role in the quality and durability of your new floor. As such, choosing the right subflooring material and installing it properly is essential to a top-performing floor.

In this guide, we’ll discuss the subfloor in detail and explain why it’s important to get it right. We’ll also touch on the differences between subfloor and underlayment and the various materials used for subfloors. 

What Is a Subfloor?

A subfloor is a structure attached to your floor joists that provides support for your surface flooring. Basically, most floors have three parts:

1. Joists

Structural joints stretch horizontally and run under the floor of every room in your house. These are the structural beams of your floor. The role of floor joists is to support a floor’s weight transfer in a structure.

2. Subflooring

This is what covers the joists. Together, the joists and the subfloor distribute the weight your floors take from above – actions like dragging heavy furniture around, flopping on the couch, your kids wrestling and more.

3. Surface floor

This is the finished floor that you actually see and walk on.

Subfloor vs. Underlayment: What’s the Difference?

Many people confuse subfloor with underlayment, but the two are not the same. Some types of flooring require a special surface between the subfloor and the surface floor. This material, sandwiched between the subfloor and the surface floor, is called underlayment.

Floor underlayment serves many purposes, including absorbing moisture, dampening noise, and smoothing out subfloor imperfections. 

Materials Used for Subfloors

Let’s go over the various materials used for the subfloor and the benefits of each.


Plywood is the most commonly used material for subflooring. It’s considered the best subfloor for hardwood flooring installation. Manufactured from thin layers of wood veneer glued together, plywood provides solid support and is cost-effective. 

Oriented Strand Board (OSB)

Oriented strand board, commonly referred to as OSB, functions like plywood. Made of chunks of wood compressed and glued together, OSB provides strong support. Another advantage of using OSB is that it requires no maintenance.


These days, most new houses have a concrete subfloor, which uses slabs to create a hard and durable surface. Finishing floorings such as stones and tiles can be directly installed over concrete, but in most cases, underlayment is needed, and new concrete slabs need adequate time to dry out before having flooring installed over them.

A concrete base provides smooth and solid floors, however, concrete slabs tend to have humps and dips in them that may not be visible to the naked eye. This means that a straight edge needs to be run across the floor to locate any flaws, and then dips can be filled with floor levelling compound and humps can be ground down.

Concrete is also not impervious to water or vapour meaning it may not be suitable for very moisture-prone areas. When used in basements and other moisture-prone areas, a moisture barrier is required.  We recommend using an underlay with a moisture barrier when installing over concrete, or laying a 100-micron thick sheet of polythene which will act as a moisture barrier.

Mixed Subflooring

Sometimes, a concrete slab is paired with OSB or plywood elements to create a composite flooring. Different combinations can be used to strengthen the subfloor, serve as a moisture barrier, or even provide a flat subfloor ready for finishing layers.

Why Is Subfloor Important?

Your finished floor is only as good as the subfloor.

That said, the quality of your subfloor directly affects the performance of the flooring, meaning a poorly installed subfloor can cause the flooring to fail or underperform.

A faulty subfloor – one that is weak, not flat, not dry, or not properly cleaned can result in many flooring problems, including:

  • Sagging
  • Uneven spots
  • Damage
  • Separation
  • Excessive shifting and movements
  • Squeaking within the floor system

Most of these issues can be prevented with proper installation and using the right subflooring materials. These issues can worsen with time and, in some cases, lead to reinstalling some parts or the entire flooring. 

For the best result, it’s important to follow the manufacturer’s instructions regarding subfloor preparation, as failing to do this will void the product warranty.

Ask the Experts at Woodland Lifestyle

Installing the right flooring based on your subflooring is important to ensure your finished floor is strong, durable, and defect-free.

If you need any assistance with subfloor installation or underlayment for your floor, get in touch with Woodland Lifestyle today. We have underlay to suit every flooring and budget.

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  • Gia Smith

    The details you shared about the subfloor were quite informative along with the differences between subfloor and underlayment. Thanks for sharing.

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